Declaration of strict_types needs to be present in every file that wants to be managed as strict. If you would be able to set that globally, there is no certainty that third-party libraries that you use are prepared for strict types.

Instead of getting errors or exception I am redirected to /, since Exception handler is providing validation errors to be displayed in HTML. (For this case I also registered my own exception handler, but it doesn't feel right)

Is there something like Laravel "API mode" which adds validation errors to the response and manages exceptions or do I need to take care of that part?